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NAME
ssl - Interface Functions for Secure Socket Layer
DESCRIPTION
This module contains interface functions for the SSL/TLS protocol. For detailed
information about the supported standards see ssl(7).
DATA TYPES
The following data types are used in the functions for SSL:
boolean() =:
true | false
option() =:
socketoption() | ssl_option() | transport_option()
socketoption() =:
proplists:property()
The default socket options are [{mode,list},{packet, 0},{header, 0},{active, true}].
For valid options, see the inet(3erl) and gen_tcp(3erl) manual pages in Kernel.
ssl_option() =:
{verify, verify_type()}
| {verify_fun, {fun(), term()}}
| {fail_if_no_peer_cert, boolean()}
| {depth, integer()}
| {cert, public_key:der_encoded()}
| {certfile, path()}
| {key, {'RSAPrivateKey'| 'DSAPrivateKey' | 'ECPrivateKey' | 'PrivateKeyInfo',
public_key:der_encoded()} | #{algorithm := rsa | dss | ecdsa, engine :=
crypto:engine_ref(), key_id := crypto:key_id(), password => crypto:password()}
| {keyfile, path()}
| {password, string()}
| {cacerts, [public_key:der_encoded()]}
| {cacertfile, path()}
| {dh, public_key:der_encoded()}
| {dhfile, path()}
| {ciphers, ciphers()}
| {user_lookup_fun, {fun(), term()}}, {psk_identity, string()}, {srp_identity,
{string(), string()}}
| {reuse_sessions, boolean()}
| {reuse_session, fun()} {next_protocols_advertised, [binary()]}
| {client_preferred_next_protocols, {client | server, [binary()]} | {client | server,
[binary()], binary()}}
| {log_alert, boolean()}
| {server_name_indication, hostname() | disable}
| {sni_hosts, [{hostname(), [ssl_option()]}]}
| {sni_fun, SNIfun::fun()}
transport_option() =:
{cb_info, {CallbackModule::atom(), DataTag::atom(), ClosedTag::atom(), ErrTag:atom()}}
Defaults to {gen_tcp, tcp, tcp_closed, tcp_error}. Can be used to customize the
transport layer. The callback module must implement a reliable transport protocol,
behave as gen_tcp, and have functions corresponding to inet:setopts/2, inet:getopts/2,
inet:peername/1, inet:sockname/1, and inet:port/1. The callback gen_tcp is treated
specially and calls inet directly.
CallbackModule =:
atom()
DataTag =:
atom()
Used in socket data message.
ClosedTag =:
atom()
Used in socket close message.
verify_type() =:
verify_none | verify_peer
path() =:
string()
Represents a file path.
public_key:der_encoded() =:
binary()
ASN.1 DER-encoded entity as an Erlang binary.
host() =:
hostname() | ipaddress()
hostname() =:
string() - DNS hostname
ip_address() =:
{N1,N2,N3,N4} % IPv4 | {K1,K2,K3,K4,K5,K6,K7,K8} % IPv6
sslsocket() =:
opaque()
protocol() =:
sslv3 | tlsv1 | 'tlsv1.1' | 'tlsv1.2'
ciphers() =:
= [ciphersuite()] | string()
According to old API.
ciphersuite() =:
{key_exchange(), cipher(), MAC::hash()} | {key_exchange(), cipher(), MAC::hash(),
PRF::hash()}
key_exchange()=:
rsa | dhe_dss | dhe_rsa | dh_anon | psk | dhe_psk | rsa_psk | srp_anon | srp_dss |
srp_rsa | ecdh_anon | ecdh_ecdsa | ecdhe_ecdsa | ecdh_rsa | ecdhe_rsa
cipher() =:
rc4_128 | des_cbc | '3des_ede_cbc' | aes_128_cbc | aes_256_cbc | aes_128_gcm |
aes_256_gcm | chacha20_poly1305
hash() =:
md5 | sha | sha224 | sha256 | sha348 | sha512
prf_random() =:
client_random | server_random
srp_param_type() =:
srp_1024 | srp_1536 | srp_2048 | srp_3072 | srp_4096 | srp_6144 | srp_8192
SNIfun::fun():
= fun(ServerName :: string()) -> [ssl_option()]
named_curve() =:
sect571r1 | sect571k1 | secp521r1 | brainpoolP512r1 | sect409k1 | sect409r1 |
brainpoolP384r1 | secp384r1 | sect283k1 | sect283r1 | brainpoolP256r1 | secp256k1 |
secp256r1 | sect239k1 | sect233k1 | sect233r1 | secp224k1 | secp224r1 | sect193r1 |
sect193r2 | secp192k1 | secp192r1 | sect163k1 | sect163r1 | sect163r2 | secp160k1 |
secp160r1 | secp160r2
SSL OPTION DESCRIPTIONS - COMMON FOR SERVER AND CLIENT
The following options have the same meaning in the client and the server:
{protocol, tls | dtls}:
Choose TLS or DTLS protocol for the transport layer security. Defaults to tls
Introduced in OTP 20, DTLS support is considered experimental in this release. DTLS
over other transports than UDP are not yet supported.
{cert, public_key:der_encoded()}:
The DER-encoded users certificate. If this option is supplied, it overrides option
certfile.
{certfile, path()}:
Path to a file containing the user certificate.
{key, {'RSAPrivateKey'| 'DSAPrivateKey' | 'ECPrivateKey' |'PrivateKeyInfo',
public_key:der_encoded()} | #{algorithm := rsa | dss | ecdsa, engine :=
crypto:engine_ref(), key_id := crypto:key_id(), password => crypto:password()}:
The DER-encoded user's private key or a map refering to a crypto engine and its key
reference that optionally can be password protected, seealso crypto:engine_load/4
and Crypto's Users Guide. If this option is supplied, it overrides option keyfile.
{keyfile, path()}:
Path to the file containing the user's private PEM-encoded key. As PEM-files can
contain several entries, this option defaults to the same file as given by option
certfile.
{password, string()}:
String containing the user's password. Only used if the private keyfile is password-
protected.
{ciphers, ciphers()}:
Supported cipher suites. The function cipher_suites/0 can be used to find all ciphers
that are supported by default. cipher_suites(all) can be called to find all available
cipher suites. Pre-Shared Key (RFC 4279 and RFC 5487), Secure Remote Password (RFC
5054), RC4 cipher suites, and anonymous cipher suites only work if explicitly enabled
by this option; they are supported/enabled by the peer also. Anonymous cipher suites
are supported for testing purposes only and are not be used when security matters.
{eccs, [named_curve()]}:
Allows to specify the order of preference for named curves and to restrict their usage
when using a cipher suite supporting them.
{secure_renegotiate, boolean()}:
Specifies if to reject renegotiation attempt that does not live up to RFC 5746. By
default secure_renegotiate is set to false, that is, secure renegotiation is used if
possible, but it falls back to insecure renegotiation if the peer does not support RFC
5746.
{depth, integer()}:
Maximum number of non-self-issued intermediate certificates that can follow the peer
certificate in a valid certification path. So, if depth is 0 the PEER must be signed
by the trusted ROOT-CA directly; if 1 the path can be PEER, CA, ROOT-CA; if 2 the path
can be PEER, CA, CA, ROOT-CA, and so on. The default value is 1.
{verify_fun, {Verifyfun :: fun(), InitialUserState :: term()}}:
The verification fun is to be defined as follows:
fun(OtpCert :: #'OTPCertificate'{}, Event :: {bad_cert, Reason :: atom() | {revoked,
atom()}} |
{extension, #'Extension'{}}, InitialUserState :: term()) ->
{valid, UserState :: term()} | {valid_peer, UserState :: term()} |
{fail, Reason :: term()} | {unknown, UserState :: term()}.
The verification fun is called during the X509-path validation when an error or an
extension unknown to the SSL application is encountered. It is also called when a
certificate is considered valid by the path validation to allow access to each
certificate in the path to the user application. It differentiates between the peer
certificate and the CA certificates by using valid_peer or valid as second argument to
the verification fun. See the public_key User's Guide for definition of
#'OTPCertificate'{} and #'Extension'{}.
* If the verify callback fun returns {fail, Reason}, the verification process is
immediately stopped, an alert is sent to the peer, and the TLS/SSL handshake
terminates.
* If the verify callback fun returns {valid, UserState}, the verification process
continues.
* If the verify callback fun always returns {valid, UserState}, the TLS/SSL handshake
does not terminate regarding verification failures and the connection is
established.
* If called with an extension unknown to the user application, return value {unknown,
UserState} is to be used.
Note that if the fun returns unknown for an extension marked as critical, validation
will fail.
Default option verify_fun in verify_peer mode:
{fun(_,{bad_cert, _} = Reason, _) ->
{fail, Reason};
(_,{extension, _}, UserState) ->
{unknown, UserState};
(_, valid, UserState) ->
{valid, UserState};
(_, valid_peer, UserState) ->
{valid, UserState}
end, []}
Default option verify_fun in mode verify_none:
{fun(_,{bad_cert, _}, UserState) ->
{valid, UserState};
(_,{extension, #'Extension'{critical = true}}, UserState) ->
{valid, UserState};
(_,{extension, _}, UserState) ->
{unknown, UserState};
(_, valid, UserState) ->
{valid, UserState};
(_, valid_peer, UserState) ->
{valid, UserState}
end, []}
The possible path validation errors are given on form {bad_cert, Reason} where Reason
is:
unknown_ca:
No trusted CA was found in the trusted store. The trusted CA is normally a so called
ROOT CA, which is a self-signed certificate. Trust can be claimed for an
intermediate CA (trusted anchor does not have to be self-signed according to X-509)
by using option partial_chain.
selfsigned_peer:
The chain consisted only of one self-signed certificate.
PKIX X-509-path validation error:
For possible reasons, see public_key:pkix_path_validation/3
{crl_check, boolean() | peer | best_effort }:
Perform CRL (Certificate Revocation List) verification
(public_key:pkix_crls_validate/3) on all the certificates during the path validation
(public_key:pkix_path_validation/3) of the certificate chain. Defaults to false.
peer:
check is only performed on the peer certificate.
best_effort:
if certificate revocation status can not be determined it will be accepted as valid.
The CA certificates specified for the connection will be used to construct the
certificate chain validating the CRLs.
The CRLs will be fetched from a local or external cache. See ssl_crl_cache_api(3erl).
{crl_cache, {Module :: atom(), {DbHandle :: internal | term(), Args :: list()}}}:
Specify how to perform lookup and caching of certificate revocation lists. Module
defaults to ssl_crl_cache with DbHandle being internal and an empty argument list.
There are two implementations available:
ssl_crl_cache:
This module maintains a cache of CRLs. CRLs can be added to the cache using the
function ssl_crl_cache:insert/1, and optionally automatically fetched through HTTP
if the following argument is specified:
{http, timeout()}:
Enables fetching of CRLs specified as http URIs inX509 certificate extensions.
Requires the OTP inets application.
ssl_crl_hash_dir:
This module makes use of a directory where CRLs are stored in files named by the
hash of the issuer name.
The file names consist of eight hexadecimal digits followed by .rN, where N is an
integer, e.g. 1a2b3c4d.r0. For the first version of the CRL, N starts at zero, and
for each new version, N is incremented by one. The OpenSSL utility c_rehash creates
symlinks according to this pattern.
For a given hash value, this module finds all consecutive .r* files starting from
zero, and those files taken together make up the revocation list. CRL files whose
nextUpdate fields are in the past, or that are issued by a different CA that happens
to have the same name hash, are excluded.
The following argument is required:
{dir, string()}:
Specifies the directory in which the CRLs can be found.
max_handshake_size:
Integer (24 bits unsigned). Used to limit the size of valid TLS handshake packets to
avoid DoS attacks. Defaults to 256*1024.
{partial_chain, fun(Chain::[DerCert]) -> {trusted_ca, DerCert} | unknown_ca }:
Claim an intermediate CA in the chain as trusted. TLS then performs
public_key:pkix_path_validation/3 with the selected CA as trusted anchor and the rest
of the chain.
{versions, [protocol()]}:
TLS protocol versions supported by started clients and servers. This option overrides
the application environment option protocol_version. If the environment option is not
set, it defaults to all versions, except SSL-3.0, supported by the SSL application.
See also ssl(7).
{hibernate_after, integer()|undefined}:
When an integer-value is specified, ssl_connection goes into hibernation after the
specified number of milliseconds of inactivity, thus reducing its memory footprint.
When undefined is specified (this is the default), the process never goes into
hibernation.
{user_lookup_fun, {Lookupfun :: fun(), UserState :: term()}}:
The lookup fun is to defined as follows:
fun(psk, PSKIdentity ::string(), UserState :: term()) ->
{ok, SharedSecret :: binary()} | error;
fun(srp, Username :: string(), UserState :: term()) ->
{ok, {SRPParams :: srp_param_type(), Salt :: binary(), DerivedKey :: binary()}} | error.
For Pre-Shared Key (PSK) cipher suites, the lookup fun is called by the client and
server to determine the shared secret. When called by the client, PSKIdentity is set
to the hint presented by the server or to undefined. When called by the server,
PSKIdentity is the identity presented by the client.
For Secure Remote Password (SRP), the fun is only used by the server to obtain
parameters that it uses to generate its session keys. DerivedKey is to be derived
according to RFC 2945 and RFC 5054: crypto:sha([Salt, crypto:sha([Username, <<$:>>,
Password])])
{padding_check, boolean()}:
Affects TLS-1.0 connections only. If set to false, it disables the block cipher
padding check to be able to interoperate with legacy software.
Warning:
Using {padding_check, boolean()} makes TLS vulnerable to the Poodle attack.
{beast_mitigation, one_n_minus_one | zero_n | disabled}:
Affects SSL-3.0 and TLS-1.0 connections only. Used to change the BEAST mitigation
strategy to interoperate with legacy software. Defaults to one_n_minus_one.
one_n_minus_one - Perform 1/n-1 BEAST mitigation.
zero_n - Perform 0/n BEAST mitigation.
disabled - Disable BEAST mitigation.
Warning:
Using {beast_mitigation, disabled} makes SSL or TLS vulnerable to the BEAST attack.
SSL OPTION DESCRIPTIONS - CLIENT SIDE
The following options are client-specific or have a slightly different meaning in the
client than in the server:
{verify, verify_type()}:
In mode verify_none the default behavior is to allow all x509-path validation errors.
See also option verify_fun.
{reuse_sessions, boolean()}:
Specifies if the client is to try to reuse sessions when possible.
{cacerts, [public_key:der_encoded()]}:
The DER-encoded trusted certificates. If this option is supplied it overrides option
cacertfile.
{cacertfile, path()}:
Path to a file containing PEM-encoded CA certificates. The CA certificates are used
during server authentication and when building the client certificate chain.
{alpn_advertised_protocols, [binary()]}:
The list of protocols supported by the client to be sent to the server to be used for
an Application-Layer Protocol Negotiation (ALPN). If the server supports ALPN then it
will choose a protocol from this list; otherwise it will fail the connection with a
"no_application_protocol" alert. A server that does not support ALPN will ignore this
value.
The list of protocols must not contain an empty binary.
The negotiated protocol can be retrieved using the negotiated_protocol/1 function.
{client_preferred_next_protocols, {Precedence :: server | client, ClientPrefs ::
[binary()]}}
{client_preferred_next_protocols, {Precedence :: server | client, ClientPrefs ::
[binary()], Default :: binary()}}: Indicates that the client is to try to perform Next
Protocol Negotiation.
If precedence is server, the negotiated protocol is the first protocol to be shown on
the server advertised list, which is also on the client preference list.
If precedence is client, the negotiated protocol is the first protocol to be shown on
the client preference list, which is also on the server advertised list.
If the client does not support any of the server advertised protocols or the server
does not advertise any protocols, the client falls back to the first protocol in its
list or to the default protocol (if a default is supplied). If the server does not
support Next Protocol Negotiation, the connection terminates if no default protocol is
supplied.
{psk_identity, string()}:
Specifies the identity the client presents to the server. The matching secret is found
by calling user_lookup_fun.
{srp_identity, {Username :: string(), Password :: string()} :
Specifies the username and password to use to authenticate to the server.
{server_name_indication, HostName :: hostname()}:
Specify the hostname to be used in TLS Server Name Indication extension. If not
specified it will default to the Host argument of connect/[3,4] unless it is of type
inet:ipaddress().
The HostName will also be used in the hostname verification of the peer certificate
using public_key:pkix_verify_hostname/2.
{server_name_indication, disable}:
Prevents the Server Name Indication extension from being sent and disables the
hostname verification check public_key:pkix_verify_hostname/2
{fallback, boolean()}:
Send special cipher suite TLS_FALLBACK_SCSV to avoid undesired TLS version downgrade.
Defaults to false
Warning:
Note this option is not needed in normal TLS usage and should not be used to implement
new clients. But legacy clients that retries connections in the following manner
ssl:connect(Host, Port, [...{versions, ['tlsv2', 'tlsv1.1', 'tlsv1', 'sslv3']}])
ssl:connect(Host, Port, [...{versions, [tlsv1.1', 'tlsv1', 'sslv3']}, {fallback,
true}])
ssl:connect(Host, Port, [...{versions, ['tlsv1', 'sslv3']}, {fallback, true}])
ssl:connect(Host, Port, [...{versions, ['sslv3']}, {fallback, true}])
may use it to avoid undesired TLS version downgrade. Note that TLS_FALLBACK_SCSV must
also be supported by the server for the prevention to work.
{signature_algs, [{hash(), ecdsa | rsa | dsa}]}:
In addition to the algorithms negotiated by the cipher suite used for key exchange,
payload encryption, message authentication and pseudo random calculation, the TLS
signature algorithm extension Section 7.4.1.4.1 in RFC 5246 may be used, from TLS 1.2,
to negotiate which signature algorithm to use during the TLS handshake. If no lower
TLS versions than 1.2 are supported, the client will send a TLS signature algorithm
extension with the algorithms specified by this option. Defaults to
[
%% SHA2
{sha512, ecdsa},
{sha512, rsa},
{sha384, ecdsa},
{sha384, rsa},
{sha256, ecdsa},
{sha256, rsa},
{sha224, ecdsa},
{sha224, rsa},
%% SHA
{sha, ecdsa},
{sha, rsa},
{sha, dsa},
]
The algorithms should be in the preferred order. Selected signature algorithm can
restrict which hash functions that may be selected. Default support for {md5, rsa}
removed in ssl-8.0
SSL OPTION DESCRIPTIONS - SERVER SIDE
The following options are server-specific or have a slightly different meaning in the
server than in the client:
{cacerts, [public_key:der_encoded()]}:
The DER-encoded trusted certificates. If this option is supplied it overrides option
cacertfile.
{cacertfile, path()}:
Path to a file containing PEM-encoded CA certificates. The CA certificates are used to
build the server certificate chain and for client authentication. The CAs are also
used in the list of acceptable client CAs passed to the client when a certificate is
requested. Can be omitted if there is no need to verify the client and if there are no
intermediate CAs for the server certificate.
{dh, public_key:der_encoded()}:
The DER-encoded Diffie-Hellman parameters. If specified, it overrides option dhfile.
{dhfile, path()}:
Path to a file containing PEM-encoded Diffie Hellman parameters to be used by the
server if a cipher suite using Diffie Hellman key exchange is negotiated. If not
specified, default parameters are used.
{verify, verify_type()}:
A server only does x509-path validation in mode verify_peer, as it then sends a
certificate request to the client (this message is not sent if the verify option is
verify_none). You can then also want to specify option fail_if_no_peer_cert.
{fail_if_no_peer_cert, boolean()}:
Used together with {verify, verify_peer} by an SSL server. If set to true, the server
fails if the client does not have a certificate to send, that is, sends an empty
certificate. If set to false, it fails only if the client sends an invalid certificate
(an empty certificate is considered valid). Defaults to false.
{reuse_sessions, boolean()}:
Specifies if the server is to agree to reuse sessions when requested by the clients.
See also option reuse_session.
{reuse_session, fun(SuggestedSessionId, PeerCert, Compression, CipherSuite) ->
boolean()}:
Enables the SSL server to have a local policy for deciding if a session is to be
reused or not. Meaningful only if reuse_sessions is set to true. SuggestedSessionId is
a binary(), PeerCert is a DER-encoded certificate, Compression is an enumeration
integer, and CipherSuite is of type ciphersuite().
{alpn_preferred_protocols, [binary()]}:
Indicates the server will try to perform Application-Layer Protocol Negotiation
(ALPN).
The list of protocols is in order of preference. The protocol negotiated will be the
first in the list that matches one of the protocols advertised by the client. If no
protocol matches, the server will fail the connection with a "no_application_protocol"
alert.
The negotiated protocol can be retrieved using the negotiated_protocol/1 function.
{next_protocols_advertised, Protocols :: [binary()]}:
List of protocols to send to the client if the client indicates that it supports the
Next Protocol extension. The client can select a protocol that is not on this list.
The list of protocols must not contain an empty binary. If the server negotiates a
Next Protocol, it can be accessed using the negotiated_next_protocol/1 method.
{psk_identity, string()}:
Specifies the server identity hint, which the server presents to the client.
{log_alert, boolean()}:
If set to false, error reports are not displayed.
{honor_cipher_order, boolean()}:
If set to true, use the server preference for cipher selection. If set to false (the
default), use the client preference.
{sni_hosts, [{hostname(), [ssl_option()]}]}:
If the server receives a SNI (Server Name Indication) from the client matching a host
listed in the sni_hosts option, the specific options for that host will override
previously specified options. The option sni_fun, and sni_hosts are mutually
exclusive.
{sni_fun, SNIfun::fun()}:
If the server receives a SNI (Server Name Indication) from the client, the given
function will be called to retrieve [ssl_option()] for the indicated server. These
options will be merged into predefined [ssl_option()]. The function should be defined
as: fun(ServerName :: string()) -> [ssl_option()] and can be specified as a fun or as
named fun module:function/1 The option sni_fun, and sni_hosts are mutually exclusive.
{client_renegotiation, boolean()}:
In protocols that support client-initiated renegotiation, the cost of resources of
such an operation is higher for the server than the client. This can act as a vector
for denial of service attacks. The SSL application already takes measures to counter-
act such attempts, but client-initiated renegotiation can be strictly disabled by
setting this option to false. The default value is true. Note that disabling
renegotiation can result in long-lived connections becoming unusable due to limits on
the number of messages the underlying cipher suite can encipher.
{honor_cipher_order, boolean()}:
If true, use the server's preference for cipher selection. If false (the default), use
the client's preference.
{honor_ecc_order, boolean()}:
If true, use the server's preference for ECC curve selection. If false (the default),
use the client's preference.
{signature_algs, [{hash(), ecdsa | rsa | dsa}]}:
The algorithms specified by this option will be the ones accepted by the server in a
signature algorithm negotiation, introduced in TLS-1.2. The algorithms will also be
offered to the client if a client certificate is requested. For more details see the
corresponding client option.
{v2_hello_compatible, boolean()}:
If true, the server accepts clients that send hello messages on SSL-2.0 format but
offers supported SSL/TLS versions. Defaults to false, that is the server will not
interoperate with clients that offers SSL-2.0.
GENERAL
When an SSL socket is in active mode (the default), data from the socket is delivered to
the owner of the socket in the form of messages:
* {ssl, Socket, Data}
* {ssl_closed, Socket}
* {ssl_error, Socket, Reason}
A Timeout argument specifies a time-out in milliseconds. The default value for argument
Timeout is infinity.
EXPORTS
cipher_suites() ->
cipher_suites(Type) -> ciphers()
Types:
Type = erlang | openssl | all
Returns a list of supported cipher suites. cipher_suites() is equivalent to
cipher_suites(erlang). Type openssl is provided for backwards compatibility with
the old SSL, which used OpenSSL. cipher_suites(all) returns all available cipher
suites. The cipher suites not present in cipher_suites(erlang) but included in
cipher_suites(all) are not used unless explicitly configured by the user.
eccs() ->
eccs(protocol()) -> [named_curve()]
Returns a list of supported ECCs. eccs() is equivalent to calling eccs(Protocol)
with all supported protocols and then deduplicating the output.
clear_pem_cache() -> ok
PEM files, used by ssl API-functions, are cached. The cache is regularly checked to
see if any cache entries should be invalidated, however this function provides a
way to unconditionally clear the whole cache.
connect(Socket, SslOptions) ->
connect(Socket, SslOptions, Timeout) -> {ok, SslSocket} | {error, Reason}
Types:
Socket = socket()
SslOptions = [ssl_option()]
Timeout = integer() | infinity
SslSocket = sslsocket()
Reason = term()
Upgrades a gen_tcp, or equivalent, connected socket to an SSL socket, that is,
performs the client-side ssl handshake.
Note:
If the option verify is set to verify_peer the option server_name_indication shall
also be specified, if it is not no Server Name Indication extension will be sent,
and public_key:pkix_verify_hostname/2 will be called with the IP-address of the
connection as ReferenceID, which is proably not what you want.
connect(Host, Port, Options) ->
connect(Host, Port, Options, Timeout) -> {ok, SslSocket} | {error, Reason}
Types:
Host = host()
Port = integer()
Options = [option()]
Timeout = integer() | infinity
SslSocket = sslsocket()
Reason = term()
Opens an SSL connection to Host, Port.
When the option verify is set to verify_peer the check
public_key:pkix_verify_hostname/2 will be performed in addition to the usual
x509-path validation checks. If the check fails the error {bad_cert,
hostname_check_failed} will be propagated to the path validation fun verify_fun,
where it is possible to do customized checks by using the full possibilitis of the
public_key:pkix_verify_hostname/2 API. When the option server_name_indication is
provided, its value (the DNS name) will be used as ReferenceID to
public_key:pkix_verify_hostname/2. When no server_name_indication option is given,
the Host argument will be used as Server Name Indication extension. The Host
argument will also be used for the public_key:pkix_verify_hostname/2 check and if
the Host argument is an inet:ip_address() the ReferenceID used for the check will
be {ip, Host} otherwise dns_id will be assumed with a fallback to ip if that fails.
Note:
According to good practices certificates should not use IP-addresses as "server
names". It would be very surprising if this happen outside a closed network.
close(SslSocket) -> ok | {error, Reason}
Types:
SslSocket = sslsocket()
Reason = term()
Closes an SSL connection.
close(SslSocket, How) -> ok | {ok, port()} | {error, Reason}
Types:
SslSocket = sslsocket()
How = timeout() | {NewController::pid(), timeout()}
Reason = term()
Closes or downgrades an SSL connection. In the latter case the transport connection
will be handed over to the NewController process after receiving the TLS close
alert from the peer. The returned transport socket will have the following options
set: [{active, false}, {packet, 0}, {mode, binary}]
controlling_process(SslSocket, NewOwner) -> ok | {error, Reason}
Types:
SslSocket = sslsocket()
NewOwner = pid()
Reason = term()
Assigns a new controlling process to the SSL socket. A controlling process is the
owner of an SSL socket, and receives all messages from the socket.
connection_information(SslSocket) -> {ok, Result} | {error, Reason}
Types:
Item = protocol | cipher_suite | sni_hostname | ecc | session_id | atom()
Meaningful atoms, not specified above, are the ssl option names.
Result = [{Item::atom(), Value::term()}]
Reason = term()
Returns the most relevant information about the connection, ssl options that are
undefined will be filtered out. Note that values that affect the security of the
connection will only be returned if explicitly requested by
connection_information/2.
connection_information(SslSocket, Items) -> {ok, Result} | {error, Reason}
Types:
Items = [Item]
Item = protocol | cipher_suite | sni_hostname | ecc | session_id | client_random
| server_random | master_secret | atom()
Note that client_random, server_random and master_secret are values that
affect the security of connection. Meaningful atoms, not specified above, are
the ssl option names.
Result = [{Item::atom(), Value::term()}]
Reason = term()
Returns the requested information items about the connection, if they are defined.
Note:
If only undefined options are requested the resulting list can be empty.
format_error(Reason) -> string()
Types:
Reason = term()
Presents the error returned by an SSL function as a printable string.
getopts(Socket, OptionNames) -> {ok, [socketoption()]} | {error, Reason}
Types:
Socket = sslsocket()
OptionNames = [atom()]
Gets the values of the specified socket options.
getstat(Socket) -> {ok, OptionValues} | {error, inet:posix()}
getstat(Socket, OptionNames) -> {ok, OptionValues} | {error, inet:posix()}
Types:
Socket = sslsocket()
OptionNames = [atom()]
OptionValues = [{inet:stat_option(), integer()}]
Gets one or more statistic options for the underlying TCP socket.
See inet:getstat/2 for statistic options description.
listen(Port, Options) -> {ok, ListenSocket} | {error, Reason}
Types:
Port = integer()
Options = options()
ListenSocket = sslsocket()
Creates an SSL listen socket.
negotiated_protocol(Socket) -> {ok, Protocol} | {error, protocol_not_negotiated}
Types:
Socket = sslsocket()
Protocol = binary()
Returns the protocol negotiated through ALPN or NPN extensions.
peercert(Socket) -> {ok, Cert} | {error, Reason}
Types:
Socket = sslsocket()
Cert = binary()
The peer certificate is returned as a DER-encoded binary. The certificate can be
decoded with public_key:pkix_decode_cert/2.
peername(Socket) -> {ok, {Address, Port}} | {error, Reason}
Types:
Socket = sslsocket()
Address = ipaddress()
Port = integer()
Returns the address and port number of the peer.
prf(Socket, Secret, Label, Seed, WantedLength) -> {ok, binary()} | {error, reason()}
Types:
Socket = sslsocket()
Secret = binary() | master_secret
Label = binary()
Seed = [binary() | prf_random()]
WantedLength = non_neg_integer()
Uses the Pseudo-Random Function (PRF) of a TLS session to generate extra key
material. It either takes user-generated values for Secret and Seed or atoms
directing it to use a specific value from the session security parameters.
Can only be used with TLS connections; {error, undefined} is returned for SSLv3
connections.
recv(Socket, Length) ->
recv(Socket, Length, Timeout) -> {ok, Data} | {error, Reason}
Types:
Socket = sslsocket()
Length = integer()
Timeout = integer()
Data = [char()] | binary()
Receives a packet from a socket in passive mode. A closed socket is indicated by
return value {error, closed}.
Argument Length is meaningful only when the socket is in mode raw and denotes the
number of bytes to read. If Length = 0, all available bytes are returned. If Length
> 0, exactly Length bytes are returned, or an error; possibly discarding less than
Length bytes of data when the socket gets closed from the other side.
Optional argument Timeout specifies a time-out in milliseconds. The default value
is infinity.
renegotiate(Socket) -> ok | {error, Reason}
Types:
Socket = sslsocket()
Initiates a new handshake. A notable return value is {error,
renegotiation_rejected} indicating that the peer refused to go through with the
renegotiation, but the connection is still active using the previously negotiated
session.
send(Socket, Data) -> ok | {error, Reason}
Types:
Socket = sslsocket()
Data = iodata()
Writes Data to Socket.
A notable return value is {error, closed} indicating that the socket is closed.
setopts(Socket, Options) -> ok | {error, Reason}
Types:
Socket = sslsocket()
Options = [socketoption]()
Sets options according to Options for socket Socket.
shutdown(Socket, How) -> ok | {error, Reason}
Types:
Socket = sslsocket()
How = read | write | read_write
Reason = reason()
Immediately closes a socket in one or two directions.
How == write means closing the socket for writing, reading from it is still
possible.
To be able to handle that the peer has done a shutdown on the write side, option
{exit_on_close, false} is useful.
ssl_accept(Socket) ->
ssl_accept(Socket, Timeout) -> ok | {error, Reason}
Types:
Socket = sslsocket()
Timeout = integer()
Reason = term()
Performs the SSL/TLS server-side handshake.
Socket is a socket as returned by ssl:transport_accept/[1,2]
ssl_accept(Socket, SslOptions) ->
ssl_accept(Socket, SslOptions, Timeout) -> {ok, Socket} | ok | {error, Reason}
Types:
Socket = socket() | sslsocket()
SslOptions = [ssl_option()]
Timeout = integer()
Reason = term()
If Socket is a socket(): upgrades a gen_tcp, or equivalent, socket to an SSL
socket, that is, performs the SSL/TLS server-side handshake and returns the SSL
socket.
Warning:
The listen socket is to be in mode {active, false} before telling the client that
the server is ready to upgrade by calling this function, else the upgrade succeeds
or does not succeed depending on timing.
If Socket is an sslsocket(): provides extra SSL/TLS options to those specified in
ssl:listen/2 and then performs the SSL/TLS handshake.
sockname(Socket) -> {ok, {Address, Port}} | {error, Reason}
Types:
Socket = sslsocket()
Address = ipaddress()
Port = integer()
Returns the local address and port number of socket Socket.
start() ->
start(Type) -> ok | {error, Reason}
Types:
Type = permanent | transient | temporary
Starts the SSL application. Default type is temporary.
stop() -> ok
Stops the SSL application.
transport_accept(ListenSocket) ->
transport_accept(ListenSocket, Timeout) -> {ok, NewSocket} | {error, Reason}
Types:
ListenSocket = NewSocket = sslsocket()
Timeout = integer()
Reason = reason()
Accepts an incoming connection request on a listen socket. ListenSocket must be a
socket returned from ssl:listen/2. The socket returned is to be passed to
ssl:ssl_accept[2,3] to complete handshaking, that is, establishing the SSL/TLS
connection.
Warning:
The socket returned can only be used with ssl:ssl_accept[2,3]. No traffic can be
sent or received before that call.
The accepted socket inherits the options set for ListenSocket in ssl:listen/2.
The default value for Timeout is infinity. If Timeout is specified and no
connection is accepted within the given time, {error, timeout} is returned.
versions() -> [versions_info()]
Types:
versions_info() = {app_vsn, string()} | {supported | available, [protocol()]
Returns version information relevant for the SSL application.
app_vsn:
The application version of the SSL application.
supported:
TLS/SSL versions supported by default. Overridden by a version option on
connect/[2,3,4], listen/2, and ssl_accept/[1,2,3]. For the negotiated TLS/SSL
version, see ssl:connection_information/1 .
available:
All TLS/SSL versions supported by the SSL application. TLS 1.2 requires
sufficient support from the Crypto application.
SEE ALSO
inet(3erl) and gen_tcp(3erl)